


How Deep Is Your Love

by erenfuckinjaeger



Category: Shingeki no Kyojin | Attack on Titan
Genre: Alternate Universe, Arranged Marriage, Enemies to Lovers, Eventual Fluff, Eventual Romance, Eventual Smut, Fantasy, M/M, Merfolk AU, Other Additional Tags to Be Added, Slow Burn
Language: English
Status: In-Progress
Published: 2020-02-23
Updated: 2020-05-10
Packaged: 2021-02-28 03:54:15
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,754
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22867438
Author URL: https://archiveofourown.org/users/erenfuckinjaeger/pseuds/erenfuckinjaeger
Summary: 'Get married!' Eren's parents had said. 'Form an alliance with the neighboring clan!' they'd said. Sure, it was good for his people, but what about what was good for Eren? Being married off to the seemingly cold and unfeeling prince of the Northern Warrior Clan seemed the farthest thing from it.
Relationships: Levi/Eren Yeager
Comments: 19
Kudos: 137





	1. Chapter 1

**Author's Note:**

> this is my first time writing a fic like this lmao but i really wanted to and big thank you to dinklebert for helping me come up with this idea and helping me world build and all that good stuff! and being my beta, you're the best <3

“This is bullshit,” Eren hisses as an extravagant piece of jewelry made of intricately strung together pearls and gems is draped over his neck, the strands cascading down his torso. The finishing touch is a beautiful crown made up of a mix of turret, cerith, and wentletrap shells that’s placed on top of his head.

“Nonsense,” his mother dismisses with a wave of her hand, a soft smile on her face as she reaches up to fix a strand of hair that’s fallen over his collarbone. “I think you look quite handsome.”

Before Eren can open his mouth to reply, his two closest friends, Armin and Krista, make their way into the room. They bow when Carla turns to them and she gives them a nod. 

"We just wanted to say our goodbyes, if that's alright," Krista says with a sad smile and Armin nods his head in agreement.

"Of course," Carla answers. She gives Eren an affectionate pat on the cheek and turns to the other servants in the room to dismiss them. As she leaves the room, she gives the two other merfolk hugs, explaining that they don't have too much time to linger.

Once his mother is out of earshot, Eren releases a groan, hands rubbing over his face.

"It'll be okay, Eren," Armin offers comfortingly. "I'm sure it won't be _that_ bad. Maybe he’s nicer than he looks…”

The prince scoffs, "Considering that I’ve met him before at the engagement dinner, he is not as nice as he looks." Eren frowns, turning to look himself over in the long mirror. “But I suppose that it could be worse. At least our mothers get along nicely.”

Krista hums. “Well at least he’s handsome, you gotta give him that.”

Eren gives her a glare through the mirror reflection as he says, “Not helping.”

Armin chuckles and Eren turns around to face his friends. A moment of silence goes by before the merman sighs, the irritation falling from his face and is replaced with a look of sorrow. Krista caves first and wraps her arms around her friend, careful of the jewelry decorating his torso. Armin is next to join their small group hug. 

The prince feels his heart lurch in his chest and he holds his friends tightly, refusing to let himself cry despite how much the action calls to him. With a sigh, he lets them go, a sad smile coming to his lips when Krista wipes tears from her eyes and apologizes.

“I’m going to miss you guys,” he says, voice thick with emotion.   
“We’ll visit as soon as we can,” Armin reassures. 

Eren nods. There’s a knock at the threshold of the room and the three merfolk look up to see Carla waiting. “It’s time.”

Armin and Krista give Eren one last smile as they turn, bowing before Carla and make their way out of the room. Eren lets out a shaky breath, swallowing back his emotions. He takes his mother’s arm, letting her lead him out to the ceremony. 

He can’t deny that it’s beautiful; there are large sea anemone that open and close in patterns, small fish that dart in and out of the seaweed swaying around in the current. Colorful flower arrangements made of corals and water plants decorate the wedding arch, also decorated with beautiful pearls and shiny shells. A bloom of jellyfish flitter around as a finishing touch.

Once Eren and his mother come into view, a soft melody begins from the choir that’s standing off to the side of the wedding arch. All eyes are turned to the pair and Eren hesitates for a moment. If not for his mother there with him, he would have turned around and swam away. 

Eren looks around at all the different pairs of eyes watching him, swallowing against the lump in his throat until his eyes finally slide up to the merman waiting at the altar for him. His face is indifferent, bored gaze looking somewhere past Eren rather than taking in the brunet’s beauty, as he should be.

_'It took me hours to get ready and my husband-to-be won’t even look at me?’_ Eren asks himself while managing to keep a fake smile on his face. 

“Why does he look like he wants to murder someone?” Eren whispers to his mother, glancing over at her.

Carla rolls her eyes, swattin Eren’s hand in reprimand. “Be nice,” she warns. “He’s about to be your new spouse.”

Eren turns his attention back to Levi, their eyes connecting for a brief moment before the other merman turns his eyes to Pastor Nick, who gives the merman a nod of acknowledgement. Eren feels his eye twitch, huffing a breath through his nose, irked at the lack of reaction he’s gotten so far from the merman at the altar.

“Well look at him, he’s so dull and aloof,” he mumbles, earning a chuckle from his mother. “He is hot, though,” Eren adds on as an afterthought.

Carla hums in amusement. “Yes, you’ll make very beautiful babies.”

“Mom!” Eren hisses, ducking his head as his face and ears burn. Carla chuckles and pats Eren’s hand that’s wrapped around her arm. 

They come to a stop at the altar and Carla reluctantly releases her hold on Eren’s arm. She turns to him, a warm, kind smile on her face and she reaches up with a hand to pat his cheek before leaning in to kiss the other one. The merman squeezes his mother’s free hand, a silent plea not to let him go despite knowing that she must.

Once the queen has backed away, Eren turns to his father who waits for him next to the altar steps. Grisha offers a sad smile, giving his son a lingering hug. “We love you,” he whispers in Eren’s ear as he pulls away and adjusts the prince’s crown.

Eren blinks rapidly, already feeling tears beginning to well up in his eyes. It’s not even because he’s getting married, but rather, he’s being whisked away to a new home and clan that he’s never seen or met before. 

Sucking in a deep breath, Eren turns and makes his way up the altar and stops before Pastor Nick and his husband-to-be. Levi’s face continues to remain expressionless, even as his eyes meet Eren’s. 

“Dearly beloved, merfolk of all kinds,” Pastor Nick begins, earning the attention of everyone in attendance, including the two merman waiting before him, “we are brought together on this day to view a beautiful ceremony: the union of Levi Ackerman from the North Warrior clan and Eren Jaeger from the Coral clan to become one with each other for the rest of their lives.”

Eren has to keep himself from rolling his eyes at the pastor’s speech. He keeps his eyes cast downward, observing the scars littered across Levi’s tail. His eyes trail up, following the scars until they disappear under the polished cuirass covering Levi’s torso. When Eren’s eyes reach Levi’s face, he takes into account the large gash across his face and over his eye that hadn’t been there the last time Eren had seen him.

Nick continues with his speech, earning the blessing from Eren’s parents as well as Levi’s mother who’s sat next to Carla, both queens smiling proudly at their sons.

“Levi and Eren, please join hands,” Nick says, looking between both mermen that snap their attention to him. Biting his tongue, Eren sticks his hands out first, urging Levi to take them as he glances down at them. 

The merman clenches his jaw, reaching out to take hold of Eren’s hands, and a shiver runs down Eren’s spine from the coldness of Levi’s fingers. 

Pastor Nick continues, focusing on Levi as he asks, “Under the eyes of King Grisha and Queen Carla of the Coral Clan and Queen Kuchel of the North Warrior Clan; Levi, do you take Eren to be your lawfully wedded Husband? Do you promise to love and support him as long as you both shall live, for better or for worse?”

The merman gives a curt nod. “I do.” His voice is low and smooth, just as nice as Eren remembers, though it doesn’t make up for the fact that the merman is still an ass.

“Eren, do you take Levi to be your lawfully wedded Husband? Do you promise to love and support Levi as long as you both shall live, for better or for worse?”

Eren feels himself hesitate for a moment, and while he wants to say no, he knows that he can and instead nods with a soft, “I do.”

“Very well, let us proceed to the exchanging of vows. Levi, you will go first.”

The merman nods, dropping Eren’s hands without a second thought. He reaches across his body with his arm, fingers wrapping around the handle of the sword sheathed in its scabbard, drawing it out with a _shwing_ sound that echoes in Eren’s ears as he watches with wide eyes. 

Levi bows , holding out his arms with the sword resting on both of his palms. Eren stares at the weapon presented before him, unsure if he’s supposed to take it or not, but thankfully Levi speaks up before Eren has a chance to do anything.

“Eren, I pledge to you my body, heart and soul, and with these things, I vow to protect and honour you for all our days together. I take you with all of your faults and strengths, and offer myself with my own, so that we may be balanced, as the hilt and blade of a sword.”

Had the situation been different and Eren had known the other merman for longer, he could say that the gesture is romantic even though it’s just simply part of the marriage tradition within Levi’s clan. Nevertheless, Eren smiles when Levi looks up to meet his eyes. “Thank you.”

Eren decides to move onto his gift, nodding towards one of the servants that stands by waiting with a large clam in her hands. She swims over to him and opens the clam, revealing a dark piece of thread decorated with different types of shells and a shark tooth that dangles in the middle.

“I figured you wouldn’t want a pearl,” Eren mentions, “so I thought that a shark tooth would do just fine.” Levi wordlessly leans forward to allow Eren to drape the piece of jewelry over his neck and tie it in place as he continues to speak. 

“Levi, this necklace represents my promise of love and friendship, a reminder that I am with you always, if not in body, then in mind and spirit. I vow to respect and honour you, to share my life with you so that we may grow together as one.”

Pulling away, Eren finds that he’s rather proud of the necklace that he’s made. The dark colored shells contrast with Levi’s skin tone in a way to make the jewelry stand out. Eren thinks that it looks nice on him. Levi reaches up, his fingers feeling where the shark tooth lies against his collarbone and he gives Eren a nod.

Pastor Nick smiles at both Eren and Levi, clapping his hands together. “By the power vested in me, under the eyes of King Grisha, Queen Carla and Queen Kuchel, I now pronounce you Husband and Husband. You may now kiss!”

Eren’s heart leaps up into his throat, looking back at Levi. For a moment, the two hold eye contact before Eren decides to lean in first, pleasantly surprised that Levi meets him in the middle. 

The kiss is soft and even though it only lasts a couple seconds, Eren’s lips tingle as they pull away. There’s a round of applause and cheering from the crowd, pulling Eren away from his daze and the two mermen face forward, joining hands. 

“Mermaids and mermen, it is with great honor that I may officially present you with Princes Mr. and Mr. Ackerman!” Nick exclaims from behind them, clapping along with the crowd.

Eren and Levi make their way down the aisle, the merfolk bowing to them, giving excited smiles, farewells, and well wishes. Levi gives nods of acknowledgement and thanks while Eren returns the smiles, though his is a bit strained. 

His heart that had once leaped up to his throat now drops to his stomach as they come up to the chariot waiting to whisk him off to his new married life.


	2. Chapter 2

**Summary for the Chapter:**

> Eren and Levi chat a little

**Notes for the Chapter:**

> the world is in shambles, so here u go :D

Upon settling into the chariot, Eren is able to give one last wave goodbye to his family and friends before the driver shouts a command at the dolphins to take off. He watches his home village get smaller in the distance until he cannot see it anymore and lets out a sigh. 

Levi sits silently across from him, inspecting his nails, not sparing Eren so much as a glance. Eren waits for another moment longer, thinking that maybe Levi will actually initiate a conversation with him for once and show _some_ interest in him. It’s all for naught, of course, when the merman begins talking to the driver of the chariot instead of his new husband.

Eren blinks a couple times, bristling in his spot and clears his throat. Levi cuts himself off, finally flicking his eyes in Eren’s direction. They meet his eyes and he arches a brow, face remaining impassive as he asks, “Is there something you would like to say? Might relieve the constipated look on your face.”

“Yes,” Eren says, jutting his chin out and crosses his arms over his chest, careful of the jewelry. “You have yet to compliment me or say anything.”

Levi rolls his eyes, returning his attention back to the blade in his lap. “Well, what are you expecting me to say? You look like a bride.”

Eren narrows his eyebrows. “What’s got your tail in a knot?” he asks irritably and Levi gives an exasperated sigh, cursing under his breath and gives Eren his full attention.

“I’m not sure about you, but I for one, am not so thrilled about being forced into a marriage. Especially with someone so delicate. Am I expected to just follow you around like your personal bodyguard and make sure that you don’t injure yourself?” He scoffs with a shake of his head.

Eren is taken aback, mouth agape as he sputters. “I am not _delicate!_ ” he exclaims. “I can take care of myself, thank you very much!” He reaches up to adjust the crown on his head, unfortunately pricking himself on one of the shells and pulls back with a hiss, mumbling about how sharp the damn thing is. 

Levi rolls his eyes once more with a shake of his head. “Yeah, sure,” he replies, unaffected by Eren’s dark glare as the merman sucks his finger into his mouth to stop the bleeding.

It would be just his luck to hurt himself on something so small right after defending himself. Eren bristles in his seat once more at Levi’s comment, deciding that it won’t be worth his breath to argue. He wonders what he had done to make Levi more frigid towards him compared to the last few times they had previously met.

When his father had announced the plan that Eren would be marrying the Northern Clan Prince, Eren had been less than thrilled. Of course he knew the day would come when his father would present such an idea to him, but he did not expect it to be a merman outside of their own clan. He hadn’t been given much time to process the information when Levi and his mother, Kuchel, arrived at the palace for the first time.

 _’Damn,’_ Eren thought when he first saw the other merman, but remained quiet next to his mother.

Introductions were thrown around and when it was Eren’s turn, he gave a charming smile. “It’s a pleasure to meet you,” he’d said.

“Likewise,” Levi said in reply, giving a subtle nod, but nothing else.

Eren had been caught off guard, deciding that Levi’s standoffish demeanor was due to being in an unknown place and being forced to converse with other merfolk he didn’t know. The rest of that day, however, Levi had remained detached, showing no interest in any conversation that Eren had tried to initiate. He had only been polite when he needed to be, but aside from those times, Eren had been given the vibe that Levi would rather be eaten by a squid than being forced to talk with his husband-to-be.

During his childhood, Eren had decided that he would want a big, grand wedding whenever the time came to be married; he might as well make the most of it. Eren had thought he would be in love with his future spouse, or have any sort of romantic attraction, but, he also had not expected to end up with a spouse with such a sour disposition. Even if both Eren and Levi decided there was nothing between them, it wasn’t as though they could divorce. He’s not sure about Levi’s clan culture, but with Eren’s, separation between spouses was uncommon and looked down upon.

The merman glances over at Levi who is talking with the chariot driver once again. Part of him begins to wonder if anything will ever bloom between him and Levi. Will Levi eventually warm up to Eren? Could they become friends? Eren would at least like them to be able to tolerate each other so that his life doesn’t become completely miserable. He already knows the lack of sun will damper his mood. 

Will Levi even let Eren go up to the surface without permission?

Eren blinks, shaking his head as if to erase the thought. Just because they’re now married does not make Levi the one in charge. Eren refuses to sit around and be some sort of pretty house decoration or a baby factory. The last thing he wishes to do is cause a fight between himself and his husband that creates more tension between them. Levi doesn’t seem the type to make Eren stay at home, however, he probably couldn’t care less about what Eren did in his free time. Maybe he would hope that Eren gets attacked or eaten by a predator so that they won’t have to be married any longer.

A frown comes to Eren’s face and he sits up straighter, wondering where the gruesome thought had come from.

“Don’t shit yourself,” Levi comments, pulling Eren back from his gaze. 

Eren’s frown shifts into a glare. “Do you ever have anything nice to say?”

Levi gives an offhanded shrug. “To you? Not at the moment.”

A huff blows through Eren’s nose and he opens his mouth to respond but is cut off when a large, green fish swims past and under the chariot. Eren’s eyes go wide, watching as it appears again, closer than before. 

“Uh…” he says eloquently and Levi arches a brow, looking over to see what Eren’s eyes are glued to.

“What? You’ve never seen an eel before?” Levi asks and Eren shakes his head vehemently. Looking back at the eel that swims alongside the chariot, Levi begins reaching out to it but stops when Eren shrieks.

“No, Levi! Don’t touch it!”

Levi blinks at the other merman, a look of confusion crossing his face before he rolls his eyes, ignoring Eren’s plea and grabs the creature with ease. If possible, Eren’s eyes widen even more as Levi holds the eel closer to his face, examining it before looking back to Eren. He begins to move his arm towards Eren but the merman shakes his head violently. 

“No, no, no! Don’t—I don’t—Levi—no!” 

“C’mon, Eren, just touch it. It won’t hurt you.” Levi urges the eel towards Eren again. 

“Ew, no, I’d rather not,” Eren says, his voice shaky. His eyes flicker between the eel and Levi, and the merman must see the distress in Eren’s eyes because he backs away and lets the eel go. 

They both watch as it swims away, disappearing into the dark water and Eren lets out a relieved sigh. Levi shakes his head and thankfully holds his tongue from saying anything, giving Eren a moment to breathe. 

Eren looks around at their dark surroundings; it’s gotten progressively darker the farther they go and he sees more and more strange looking fish that he’s never seen in or around his home village. 

“That eel wouldn’t have hurt you,” Levi says offhandedly.. “It was only a baby.”

“It’s not like I would know that!” Eren hisses. “I’m not exactly a local.”

Levi snorts. “If you’re afraid of a baby eel, then you’re in a world of shock down here.”

Eren narrows his eyes. “Oh, thanks. That’s _real_ reassuring,” he bites.

“We’ve almost arrived, sirs,” the chariot driver says, breaking the tension between the newlyweds and Levi gives him a thanks. 

Eren’s heart leaps into his throat, his pulse quickening as he realizes that he’s almost to his new home. The environment around him isn’t exactly homey; it’s just as dark and gloomy as he thought it would be. At least it matches his husband’s personality. 

_’What will Levi’s people think of me?’_ Eren asks himself, chewing on his bottom lip nervously. He knows that Kuchel likes him, but if his husband doesn’t, then Eren is sure the rest of them won’t either. It’s not common for Eren’s species of merpeople to be found in deeper water, considering their need of sun and the sea flora that grow near the surface.

Still, Eren’s stomach churns at the idea of living down here in cold water with an even colder husband, and no friends. The whole clan couldn’t be exactly like Levi, could they? If Kuchel is a nice mermaid then there has to be others too that Eren could befriend. Or, at least, that’s what he’s hoping.

Eren looks up when he sees a faint glow becoming brighter, showcasing the new city where Eren will be living. The lights are made up of different types of glowing fish, including jellyfish and at least Eren is able to take a look around as they slowly come to a stop. 

There is a small crowd of merpeople waiting, most likely to welcome Levi back home. Most have pale skin similar to Levi's, their tails darker colors than what Eren has seen. 

“Welcome home,” the chariot driver says, turning to the mermen behind him. 

Eren gives him a tense smile in return. Welcome home indeed.

**Author's Note:**

> well hello! thank you for reading and if you liked it, please let me know through kudos or a comment or something! you guys are amazing and i hope to see you next chapter!!


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